Comprehensive Solid Waste Management Plan open house

Determining a new method for waste disposal requires that the County evaluate the possible environmental impacts of each option. This evaluation is known as the State Environmental Policy Act (SEPA) process and begins with a scoping period.

During scoping, the public will be able to tell the project team what should be studied in an environmental impact statement (EIS). The community will have the opportunity to comment on the proposed disposal options and share potential environmental and community impacts that the County should consider during its analysis and propose mitigation to reduce or avoid possible impacts.

Project background

The King County Solid Waste Division is updating its state-mandated Comprehensive Solid Waste Management Plan, which guides how King County manages garbage and recycling. The solid waste system serves 37 cities and the unincorporated areas of King County.

As part of that process, the Division studied five potential long-term waste disposal methods to prepare for the eventual closure of the Cedar Hills Regional Landfill, expected in the next 10-20 years.

In accordance with SEPA, the Division is now preparing a non-project EIS focused on two options found to be viable, Waste Export by Rail and Mass Burn (Waste-to-Energy).

What is a Comprehensive Solid Waste Management Plan?

A Comprehensive Solid Waste Management Plan, or Comp Plan, is a long-term planning document that outlines how a region will manage solid waste, such as garbage, recycling, and compost, for the next 20 years. It is required by state law and developed by the local solid waste authority in coordination with cities and other stakeholders.

The plan usually includes:

• Current system overview: How solid waste is collected, transferred, and disposed of.
• Future projections: Expected population growth, waste generation trends, and service needs.
• Goals and policies: For waste reduction, recycling, environmental protection, and sustainability.
• Facility planning: Where future transfer stations, recycling centers, or landfills might be needed.
• Disposal options: Long-term strategies for managing waste after landfills are full.
• Public and environmental health considerations: Health and environmental risks, such as air emissions, groundwater protection, and noise.
• Compliance: How the system meets all local, state, and federal regulations.
• Waste composition: Data on what materials are currently disposed of by homes, businesses, and industries.
• Metrics and performance: Current solid waste tonnages and how success is measured over time.
• Financing: How solid waste infrastructure and operations are paid for, including rates, fees, and funding strategies.

The Comp Plan serves as a roadmap for decision-making, budgeting, and infrastructure investments.

Updating the Comp Plan

The Cedar Hills Regional Landfill, King County's primary waste disposal site, is expected to reach capacity within 10–20 years. Once the landfill is full, King County will no longer have a local disposal option, making planning for what comes next critical.

Updating the Comprehensive Plan allows King County to:

• Identify and evaluate long-term disposal options to replace Cedar Hills once it closes.
• Prepare infrastructure and services for a smooth transition to a new system.
• Ensure environmental protection and regulatory compliance under state laws.
• Engage the public in decisions affecting waste services and costs for decades.
• Secure funding and partnerships for major projects that may take years to build or implement.

King County's Comp Plan update is a tool for making informed, community-supported decisions about the future of waste management before Cedar Hills runs out of space.

Long-term disposal options

King County is planning ahead by exploring long-term, sustainable options for managing waste and ensuring a resilient future for the region. A study was conducted that evaluated five long-term waste disposal options to determine the best option for Cedar Hills. The five options studied were:

• Gasification is a process that turns organic materials like wood or plant waste into a gas called "syngas." It's done by heating the material to very high temperatures in an area with little oxygen. The gas produced, mainly hydrogen and carbon monoxide, can be used as fuel or to make other products. The study found:
• No existing facilities meet King County's disposal needs.
• Operating history is unproven at scale, particularly for municipal solid waste.
• Most current facilities are pilot scale only.

• Pyrolysis is a process that breaks down materials, like wood, plastic, or rubber, by heating them in the absence of oxygen. This causes the materials to break down and produce gases, oils, and solid residues like charcoal. The products can be used for energy or other purposes, such as creating biofuels or materials for industry. The study found:
• Similar to gasification, there are no operational facilities that meet King County's requirements.
• Lack of a proven track record at the scale and with the waste material needed.
• Most applications remain at the pilot stage.

• Refuse-Derived Fuel (RDF) is a type of fuel made from waste materials, typically non-recyclable household or commercial wastes. The waste is sorted, processed, and sometimes shredded to remove any harmful materials. What's left is a fuel that can be burned to generate energy, often used as a replacement for coal. RDF can include things like paper, plastic, and textiles, which would otherwise end up in landfills. The study found:
• Proven performance only with homogeneous (uniform) waste material.
• There are no guaranteed markets for RDF made from municipal solid waste.
• RDF can be used instead of coal, which is better for the environment but may be more harmful to human health due to burning of plastics.

• Waste Export by Rail involves loading garbage onto trains and shipping it to a landfill in another part of the country that has space. Exporting waste by rail is a common practice among Puget Sound urban areas, particularly for counties lacking nearby landfill options. The study found:
• Proven long-term operational performance.
• Compatible with a wide range of municipal solid waste types and all tonnage scenarios.
• Strong compatibility with King County's existing waste collection system.
• Identified as one of the most viable long-term options for managing 2040 projected tonnage.

• Mass Burn (Waste-to-Energy) involves burning garbage at high temperatures in specially designed facilities to reduce waste volume and generate electricity. This method includes a rail transportation component so, regardless of the chosen disposal method, the County will still rely on rail to export waste. It significantly reduces the amount of waste sent to landfills, but it also raises concerns about human health impacts, costs, and site location. The study found:
• Long-standing operational history with the ability to handle a broad range of municipal solid waste.
• Scales well to King County's projected tonnage levels.
• Highly compatible with existing waste infrastructure and collection methods.

Due to their inability to reliably handle projected tonnage and/or waste types, gasification, pyrolysis, and RDF were not recommended for further consideration by the Solid Waste Division and its advisory committees - Metropolitan Solid Waste Advisory Committee and Solid Waste Advisory Committee. Waste export by rail and mass burn (waste-to-energy) were deemed the most probable options.

Both options are being closely studied as part of King County's environmental review and solid waste planning process. You can read the full report here.

Upcoming community outreach opportunities

The King County Solid Waste Division will host a series of in-person community meetings across King County in June and July of 2025. A virtual meeting option is also available for those who cannot attend in person. These meetings are an opportunity to learn about the Comp Plan, explore proposed waste management alternatives, ask questions, and share your input.

You can also leave a comment from June 17- July 7

In-person and virtual meeting dates:

• Third Place Commons - June 17, 6 pm to 7:30 pm
• North Bellevue Community Center (Banquet Room) - June 24, 6 pm to 7:30 pm
• Kent Commons Community Center (Mount Rainier Room) - June 25, 6 pm to 7:30 pm
• Virtual meeting, sign up to join via Zoom – July 1, 6 pm to 7:30 pm
• Skyway Library (Skyway Meeting Room) – July 2, 6 pm to 7:30 pm